AIM： Insulin-like growth factor-Ⅰ （IGF-Ⅰ） can effectively promote the proliferation of sarcoblasts, even at a low concentration, but the mechanism is still unclear. Growth cycle of sarcoblasts is detected by flow cytometry propidium iodide method （PI）. This study investigated the effect and mechanism of IGF-Ⅰ on the growth of primary and continuously subcultured human embryonic myoblasts.
METHODS： Experiments were performed at the State Key Laboratory of Biotherapy, Stem Cells and Tissue Engineering Laboratory, West China Hospital, Sichuan University and Flow cytometry Room, Department of Clinical Laboratory, Third People＇s Hospital from June to December 2004. Puerperants signed an informed consent. Fetus by induction of labor with water bag of pregnant 8-12 weeks, of either sex, were selected. Gastrocnemius and musculus quadriceps fexoris of cnemis were obtained. Sarcoblasts were isolated, purified and passaged by the method of references. The experimental procedures were approved by Hospital Ethics Committee. The primary, the 2nd, 4th and 6th passage of myoblasts were cultured in 24-well plate at 1 ～10/well in vitro. Three wells served as a group, totally 7 groups. Cells in the 1-7 groups were synchronized in serum-free F12 medium, and then incubated in medium containing 0,1, 2, 4, 8, 16, 32 μ g/L insulin-like growth factor Ⅰ （IGF-Ⅰ）. Suitable concentration of IGF-Ⅰ to promote proliferation was identified by incorporation assay. The control groups only received growth medium. The experimental groups received IGF-Ⅰ at suitable concentrations. Cells from 3 wells were counted and growth curves were observed in each group every day. Doubling time of myoblastic masses was calculated as cell generation cycle Tc. Cell cycle and time （h） of G0/G1 phase, S phase and G2M phase were detected by flow cytometry （PI method）.
RESULTS： 4-8 g/L IGF-Ⅰ were chosen to stimulate myoblasts proliferation. Sarcoblasts in experimental groups and control groups entered logarithmic growt
Journal of Clinical Rehabilitative Tissue Engineering Research